Communication systems that provide services to subscriber devices, such as Code-Division Multiple Access (CDMA) systems often base the bills for such services on the amount of services consumed or used. Therefore the systems often collect usage data corresponding to each subscriber device for billing purposes. A system element, such as a Packet Data Serving Node (PDSN), typically collects usage data, such as the number of bytes transmitted to and from each subscriber device and generates a Usage Data Record (UDR) corresponding to these bytes. However, often not all of these bytes represent “usage” by the subscriber device. For example, bytes that are transmitted due to system overhead activities arguably should not be included in the UDR. Examples of overhead include traffic that results from mobility of subscriber devices as well as radio frequency transmission errors. Both of these examples and others can increase overhead, thus bytes transmitted to and from subscriber devices that do not represent usage by the subscriber device. Clearly a need exists for methods and devices for providing more accurate billing information.